Background: Healthcare spending is highly concentrated among a small seriously ill population. Yet, most high-cost patients are not in the last year of life and, despite high spending, quality of care for this group is often low, marked by poor communication, high burden of pain and other symptoms, and preference- discordant treatments. A key subset of this seriously ill population, persons with Alzheimer's disease and related dementias, may experience the greatest burden of serious illness due to dementia's long course of illness, progressive functional impairment, and high degree of caregiver strain, the impact of which is often magnified among vulnerable and underserved subgroups. These issues are not well characterized over the course of illness and very little is known about the experience of those with both dementia and another serious illness, such as cancer or heart failure. Only by examining patient and families' experiences prospectively and over time can we begin to understand how these patterns are associated with patient care quality and family outcomes and thus appropriately target the interventions needed to improve care. Aims: Over the award period, I aim to expand my research and mentoring program by 1) building an innovative prospectively-framed sample, identified at onset of dementia, to examine patient and family outcomes (i.e., hospital and emergency department admissions, burdensome transitions, nursing home admission, and exhaustion of household wealth) over time; and 2) examining within this sample, differences in these patient and family outcomes between those with dementia compared to those who also have another serious illness (e.g., cancer). In both aims, we will also examine differences across vulnerable subgroups. Methods: Working in parallel across two nationally-representative, longitudinal cohorts, the Health and Retirement Study and the National Health and Aging Trends Study, linked to individual-level Medicare claims, we will identify incident dementia and other serious illnesses. By anchoring to the first observed date of illness, we will construct a longitudinal person-level dataset, including rich patient and family reported measures as well as healthcare claims. We will then use these data to examine the experiences and outcomes of older adults with dementia, with or without another serious illness, over time and also investigate disparities across vulnerable social and demographic subgroups. Public Health Significance: Older adults with dementia and other serious illnesses and their families are at risk for suffering due to low-quality, high-cost care, yet little prospective data on their experiences exist. This project will examine the longitudinal experience of those with dementia and their families beginning with the onset of dementia, and compare these experiences to those with another serious illness, such as cancer or heart failure. This study will also serve as a platform for mentoring junior investigators.